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Comparison
Body
Fat | Reference
How
does Tanita's Body Fat Analyzers compare with other methods
in terms of accuracy, repeatability, cost, patient convenience,
and length of procedure?"
a)
DEXA (Dual Energy X-ray Absorptiometry) This method
is extremely accurate and repeatable. It is also extremely
expensive ($80,000-100,000); and very inconvenient for patients
and users. The patient must lay supine for approximately 20-30
minutes while every section of their body is systematically
X-rayed. For practical purposes, this device is mainly used
in research studies.
b)
Hydrostatic Weighing - If done correctly, this
method is also very accurate, and the results are often repeatable.
However, the test is somewhat subjective because it relies
upon the subject's ability to expire all oxygen out of their
lungs while submerged in a tank of water. Some subjects have
been unable to totally exhale their oxygen while submerged,
thus skewing the results. Also very expensive ($25,000-$35,000
depending on type of equipment used and the underwater facility).
Obviously, the burden to the patient is substantial. Generally,
this process is repeated a number of times, and an average
is taken. This method is more suitable for research studies
due to the expense, lengthy testing procedure, and physical
burden to the subject.
c)
TANITA TBF-105 Very accurate (within +/- 2-3%
of DEXA) and offers a totally objective method of testing.
Offers consistently repeatable results (only 1% variance with
the TBF Series vs. up to 4% in Hydrostatic Weighing). Priced
at $5,500, this equipment is inexpensive as compared
to the above methods. Because the TBF Series operates like
a scale, there is literally no burden to the patient. There
is no need for a trained technician to operate the equipment,
and the entire process takes about one minute.
d)
Other BIA methods - Results
are accurate, however, they are more subjective due to the
variation of electrode placement (1 cm electrode variation
on any limb changes reading dramatically). For this reason,
this method may not give accurate trending results. The patient
must be in a supine position while electrodes and conductive
jelly are placed on the wrist and opposite ankle. This method
is used in some physician offices. However, due to the burden
to the subject and reasons listed above, it is neither as
convenient nor as objective as the newer BIA method employed
in Tanita's TBF Series Body Fat Analyzer/Scale.
e)
Calipers - Highly subjective testing relies on
a trained and certified technician testing multiple sites.
"Despite the contention that subcutaneous fat makes up
about half of the total body fat, there are no data to support
this statement. Furthermore, because there is little information
on the distribution of fat in the body of the population at
large, the validity of using skinfold equations to predict
body composition is restricted to populations from whom these
equations were derived."(1) Because this type
of test often depends on the attending technician, the caliper
method may not be suitable for trending applications or obtaining
repeatable results. The cost is minimal, ranging from $15
to $200 depending on the quality and features of the individual
caliper. The use of calipers is very intrusive; many patients
are uncomfortable with the necessary multiple site skinfold
tests.
f)
MR - Near Infra-Red - This is a relatively new
method of body composition analysis that offers a low level
of accuracy. "Numerous researchers have reported unacceptable
prediction errors (3.7% to 6.3%)."(2) "The
manufacturer's equation systematically underestimated average
body fatness by as much as 2 %BF to 10%BF. . . The degree
of underestimation of %BF appears to be directly related to
the level of body fatness."(2) The cost of
this equipment is relatively low ($1,000 - $2,500 depending
on the model). The NIR method is not burdensome to the subject.
1)
Lukaski, Henry, PhD Methods for the assessment of human
body composition: traditional and new. American Society
for Clinical Nutrition. (541) 537-556-1937
2)
Heyward, Vivian, Stolarczyk, Lisa, Applied Body Composition
Assessment (61) 56-65-1996
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